The present invention relates to a method and apparatus for controlling movement of suspended particulates and/or marine life in a body of water. More specifically, the present invention relates to a containment/exclusion boom and a method of controlling movement of suspended particulates and/or marine life.
Industrial plants and power plants utilize water from nearby water sources for cooling purposes. Consequently, a problem of the ingestion of particulates or marine life (e.g., fish, fish eggs, larvae, zebra mussels, vegetation, etc.) into the cooling system water intakes by suction, random entry, or other means is created. The same problem exists in any similar facility where water or materials in the water are required for some purpose and are obtained from water bodies containing particulates and/or marine life.
Floating barrier or containment boom systems have been devised to contain pollutants in lakes and seas. Typically, they employ a series of buoyant boom sections that have segments of curtains or skirts attached thereto. The curtains are typically made of water-impervious, non-oil-absorbent, flexible sheet material. The curtains extend downward into the water below the boom section and are usually stabilized by at least a weighted ballast integrated into the lower edge of the curtain. These systems employ various, sometimes elaborate, mechanical means for securing boom sections to curtain segments and for interconnecting boom curtain sections to form a continuous containment system. Such booms may be provided in small sections and require extensive subassembly prior to deployment, which represents an increase in labor requirements as well as an increase in deployment time. These increases represent an increased cost and delay in deployment of containment boom systems.
Some containment systems employ a series of cables, wires, and other structural supports to provide rigidity and/or stability to the curtain segments and the system as a whole. Due to the rigidity, some prior art booms are susceptible to the movement of contaminants beneath the boom curtain. When exposed to wind-generated currents, tidal currents, or wave conditions, such booms have been known to break under the load, to be overtopped by waves, or to have pollutants propelled over and under the boom. Inadequate curtain length also contributes to the passage of contaminants beneath the containment system.
Further, the materials used in these conventional containment systems may be sensitive to certain environmental conditions (e.g., pollutants, salt water, and ultraviolet light) and, thus, too quickly deteriorate. For instance, metal parts may rust and corrode. Further, these curtain fabrics may lose flexibility or crack at low temperatures, or may deteriorate due to prolonged exposure to ultraviolet light.
In addition, conventional containment systems are not adapted for use in certain exclusion applications, such as preventing suspended particulates or marine life from entering water intake systems. With most boom systems used in controlling water pollutants, water passes in two directions (i.e., during tidal fluctuations). Accordingly, any suspended particulates or marine life that may attach to the boom curtain is washed away from the boom curtain by the reversal of direction of the water flow. With the use of such conventional boom systems in controlling suspended particulates or marine life from entering a water intake, the water only passes in one direction, which means that the curtain material will become clogged with suspended particulates or marine life contained in the water and the containment system will fail. Moreover, most conventional containment systems are also not equipped to handle significant uni-directional flow rates employed in many water intake systems. The stresses placed on conventional containment system by the water flow may itself cause the containment system to fail.
U.S. Pat. No. 5,102,261 to Gunderson, III (xe2x80x9cGundersonxe2x80x9d) relates to a floating containment boom for containment and isolation of water-born pollutants. The containment boom includes a flotation unit, a ballast, a continuous curtain of at least one sheet of geosynthetic fabric, and at least two tow cords. Gunderson, however, does not disclose a satisfactory method of controlling marine life from entering water intake structures. Further, Gunderson does not disclose a means of removing fouling material from the curtain, nor does it disclose a means of preventing damage to the curtain in the event that the curtain becomes fouled by particulates or marine life.
The present invention is directed toward overcoming these deficiencies.
The present invention relates to a method of controlling movement of suspended particulates or marine life in a body of water. The method includes introducing into the body of water containing suspended particulates or marine life a containment/exclusion boom having a curtain formed of a flexible fabric that controls the passage of suspended particulates or marine life through the curtain and injecting a gas into the water in a manner effective substantially to remove fouling material from the curtain.
Another aspect of the invention relates to a method of cleaning fouling material from a boom curtain suspended in a body of water. The method includes injecting a gas into the water in a manner effective substantially to remove fouling material from the boom curtain.
A further aspect of the invention relates to a containment/exclusion boom for controlling movement of suspended particulates or marinc life in a body of water. The boom includes a support system positioned in the body of water which has a floor and a water surface. A curtain made of a flexible fabric that allows movement of water therethrough and controls the passage of suspended particulates or marine life therethrough is connected to the support system with the curtain extending substantially from the floor to a position at or above the water surface. The boom also includes a gas injection system for injecting gas into the body of water, whereby the gas substantially removes fouling material from the curtain.
According to another aspect of the present invention, the containment/exclusion boom of the present invention is suitable for reducing transmission of energy from the shock wave of an underwater explosion. This aspect relates to a method that includes introducing into a body of water a first boom system which substantially surrounds a detonation site, the first boom system having a curtain having two sheets of flexible fabric, and injecting a gas between the two sheets of flexible fabric before detonation of an underwater explosive at the detonation site.
Yet another aspect of the present invention relates to a method of filtering intake water for a plant, such as a power plant or the like. The method includes securing a containment/exclusion boom of the present invention in a body of water about a water intake system and periodically injecting a gas into the water in a manner effective substantially to remove fouling material from the curtain of the boom.
The containment/exclusion booms of the present invention are able to be used in a method of controlling marine life from entering intakes, because fouling material may be cleaned from the boom curtain. In addition, removing fouling material from the curtain reduces the stress placed on the boom by the water flow, thereby minimizing and/or preventing damage to the boom as well as preventing the curtain from being ripped away from its anchoring system.